They always do a cleanup in the patches.
- Heavensward saw us instill a leadership structure in Ishgard and add them to the grand company alliance
- Stormblood saw us instill a leadership structure in Ala Mhigo and Doma
- Shadowbringers saw us instill a leadership structure in Eulmore and phase out the Crystal Exarch
- Endwalker saw us instill a leadership structure in Garlemald and cleanup the issues in Radz
- Dawntrail will see us instill a leadership structure in Solution Nine and cleanup any other messes we made.
Hardly. They delayed it mostly due to covid because the companies they outsourced to couldn't provide the assets on time due to not working. They delayed it by a further 2 weeks because Yoshi-P wanted to add Emet-Selch's lines about the twelve and the new world, because he felt the story ended too depressingly without that glimmer of hope for the future of the game after the arc was complete.
Blue Mage additions, a Chaos Raid, an alliance raid, an extreme trial, an ultimate raid, a new dungeon, a custom delivery, a quest for doing all role quests, hildibrand, probably a beast tribe(?) and more MSQ.
If that's minimal to you then maybe it's just that not much content interests you in this game.
They tend to spend a lot of time coming up with the story (X.0 to X.3 patch) then start developing it after the X.3 patch. So by the time of 6.55 they'd already made most of it...
I remember right before Shadowbringers released, they said "5.1 is ready". But they still kept the 3.5 month delay on it because they use that time to thoroughly test it and iron out bugs.